When producing a semiconductor related product or a liquid crystal related product, a finer or multi-layer pattern has been increasingly formed on a substrate for a semiconductor device or a liquid crystal display in order to deal with a demand for an increase in degree of integration, an increase in operation speed, implementation of multifunctionality, and the like. Therefore, it has become indispensable to planarize the surface of the substrate. A coating liquid that produces a silica-based film (spin-on-glass (SOG) film) through curing has been generally used as a planarization film or an interlayer insulating film when producing a substrate for a semiconductor device or a liquid crystal display. Specifically, a coating liquid that includes an alkoxysilane hydrolysate or the like is applied to a substrate by spin coating or the like, and the resulting film is heated to remove a volatile component to obtain a silica-based film that includes an Si—O—Si bond.
Since the planarization film and the interlayer insulating film are generally heated during the substrate production process, a resin that exhibits higher heat resistance has been desired. For example, Patent Document 1 proposes a polysiloxane that includes a carbon-carbon unsaturated bond and a hydrosilyl group, and is capable of undergoing hydrosilation, as a heat-resistant resin raw material. Patent Document 1 states that various organic solvents may be used as a medium for dissolving the polysiloxane. In the examples of Patent Document 1, a mixed solvent of toluene and ethanol is used as the reaction solvent. However, Patent Document 1 states that the resulting polysiloxane could not be dissolved in toluene. Patent Document 1 does not disclose or suggest that the storage stability of the polysiloxane during or after production varies depending on the type of reaction solvent.
Patent Document 2 also discloses a polysiloxane that can be dissolved in an organic solvent and has a structure that allows hydrosilation. Patent Document 2 describes an aromatic hydrocarbon, an ether, and an ester as the reaction solvent that can be used when subjecting the raw material monomer to hydrolysis and polycondensation. Patent Document 2 describes that a lower alcohol such as methanol, ethanol, and 2-propanol may be used in combination with the above nonpolar solvent. In the examples of Patent Document 2, a mixed solvent of xylene and 2-propanol is used as the reaction solvent. Patent Document 2 does not disclose or suggest that the storage stability of the polysiloxane during or after production varies depending on the type of reaction solvent.
Patent Document 3 discloses a curable coating composition that includes a polysiloxane having a structure that allows hydrosilation, and an organic solvent that does not include a hydroxyl group, and has a boiling point of 80° C. to 130° C. Patent Document 3 states that the molecular weight of the polysiloxane may increase during storage, or the coating composition may gel, or paint coat particles may occur when the organic solvent includes a hydroxyl group.
As described above, a method has been known that subjects a raw material monomer to hydrolysis and polycondensation when producing a polysiloxane that includes a carbon-carbon unsaturated bond and a hydrosilyl group, and is capable of undergoing hydrosilation. It has also been known to use various organic solvents as the reaction solvent. But it has not been known that a capability to prevent gelation during production, and the storage stability of the polysiloxane after production vary depending on the type of organic solvent. It has been known that the storage stability of a curable coating composition containing a polysiloxane that includes a carbon-carbon unsaturated bond and a hydrosilyl group, and is capable of undergoing hydrosilation, is impaired when the curable coating composition includes an organic solvent having a hydroxyl group, and the molecular weight of the polysiloxane may increase, or gelation may occur. Specifically, selection of the reaction solvent has not been known as a means for efficiently producing a polysiloxane or product having stable quality by preventing gelation or an increase in molecular weight of the polysiloxane. Since it has been known that an organic solvent having a hydroxyl group is undesirable as the solvent included in the composition, the above documents teach away from using an organic solvent having a hydroxyl group in order to solve the above technical problem.